Tens of thousands of people were stranded Monday after Delta Air Lines flights were grounded around the globe due to a system outage.

The carrier pointed to an overnight power outage in its hometown of Atlanta, saying that has "impacted Delta computer systems and operations worldwide, resulting in flight delays."

The glitch appeared to knock Delta's automated check-in kiosks offline, forcing agents at ticket counters to manually check-in some passengers. Even with that, it was not immediately clear when flights might begin departing again for Delta.